A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Relations between tectonics and magmatology in the northern danakil depression (Ethiopia)

Barberi, F.; Borsi, S.; Ferrara, G.; Marinelli, G.; Varet, Jacques

doi:10.1098/rsta.1970.0037

Cited by 86 publications

(19 citation statements)

References 10 publications

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“…Reports suggest it may have occurred between March 1906and August 1907(Gouin, 1979. Its true location among the fissure-fed flow fields east of the Alayta shield was confirmed by Barberi et al (1970). The lava flow emitted by the eruption has not been identified for certain, but satellite images show a large, bifurcating lava flow field with one arm to the east and the other to the northeast and source vents (at 13 • 00 ′ N 40 • 41 ′ E) and a source fissure apparently oriented N (CNR-CNRS, 1973).…”

Section: Alayta (1906-1907)mentioning

confidence: 81%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

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Crustal extension at the East African Rift System (EARS) should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800) and find that 7 match the (approximate) geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic) variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement), transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief) and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes, and evolved and mixed magmas capable of explosive behavior. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g., Kone) and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g., Erta Ale), suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behavior. Eruptions within 7 km of the volcano are of relatively short duration (<100 days), but eruptions with more distal fissures tend to have lesser obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002) due to major along-rift dyking events that effectively changed the Nyamuragira stress field and the intrusion/extrusion ratios of eruptions.

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Section: Alayta (1906-1907)mentioning

confidence: 81%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

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“…The Afar region, as a candidate for the formation of a new oceanic crust, has been studied with particular attention using updated analytical methods and facilitated field exploration (e.g., Barberi et al 1970Barberi et al , 1972Barberi and Varet 1977;Makris and Rhim 1991). The highland volcanites were investigated from a petrographical, geochemical, and geochronological point of view by , Davidson and Rex (1980), Mohr and Zanettin (1988), Woldegabriel et al (1990), Ebinger et al (1993), Hofmann et al (1997), Rochette et al (1998), Pik et al (1998), Kieffer et al (2004), andBeccaluva et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Geology of Ethiopia: A Review and Geomorphological Perspectives

Abbate

Bruni

Sagri

2015

World Geomorphological Landscapes

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The Ethiopian region records about one billion years of geological history. The first event was the closure of the Mozambique ocean between West and East Gondwana with the development of the Ethiopian basement ranging in age from 880 to 550 Ma. This folded and tilted Proterozoic basement underwent intense erosion, which lasted one hundred million years, and destroyed any relief of the Precambrian orogen. Ordovician to Silurian fluviatile sediments and Late Carboniferous to Early Permian glacial deposits were laid down above an Early Paleozoic planation surface. The beginning of the breakup of Gondwana gave rise to the Jurassic flooding of the Horn of Africa with a marine transgression from the Paleotethys and the Indian/Madagascar nascent ocean. After this Jurassic transgression and deposition of Cretaceous continental deposits, the Ethiopian region was an exposed land for a period of about seventy million years during which a new important peneplanation surface developed. Concomitant with the first phase of the rifting of the Afro/Arabian plate, a prolific outpouring of the trap flood basalts took place predominantly during the Oligocene over a peneplained land surface of modest elevation. In the northern Ethiopian plateau, huge Miocene shield volcanoes were superimposed on the flood basalts. Following the end of the Oligocene, the volcanism shifted toward the Afar depression, which was experiencing a progressive stretching, and successively moved between the southern Ethiopian plateau and the Somali plateau in correspondence with the formation of the Main Ethiopian Rift (MER). The detachment of the Danakil block and Arabian subcontinent from the Nubian plate resulted in steep marginal escarpments marked by flexure and elongated sedimentary basins. Additional basins developed in the Afar depression and MER in connection with new phases of stretching. Many of these basins have yielded human remains crucial for reconstructing the first stages of human evolution. A full triple junction was achieved in the Early Pliocene when the MER penetrated into the Afar region, where the Gulf of Aden and the Red Sea rifts were already moving toward a connection via the volcanic ranges of northern Afar. The present-day morphology of Ethiopia is linked to the formation of the Afar depression, MER, and Ethiopian plateaus. These events are linked to the impingement of one or more mantle plumes under the Afro-Arabian plate. The elevated topography of the Ethiopian plateaus is the result of profuse volcanic accumulation and successive uplift. This new highland structure brought about a reorganization of the East Africa river network and a drastic change in the atmospheric circulation.

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“…Expeditions in the 1970s documented Afar volcanism at reconnaissance scale (Barberi et al 1974a(Barberi et al , b, 1970Civetta et al 1975). Barberi et al (1970) distinguished between the axial ranges (Erta'Ale and Alayta) and marginal ranges exemplified by Ma'Alalta and Dabbahu (Field et al 2012b(Field et al , 2013Wiart and Oppenheimer 2005). The latter are generally more alkaline and show signs of crustal contamination (Civetta et al 1975;De Fino et al 1978;Ottonello et al 1978).…”

Section: Regional Backgroundmentioning

confidence: 99%

The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

Donovan

Blundy

Oppenheimer

et al. 2017

Contrib Mineral Petrol

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The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar.

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A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Relations between tectonics and magmatology in the northern danakil depression (Ethiopia)

Cited by 86 publications

References 10 publications

Historical Volcanism and the State of Stress in the East African Rift System

Historical Volcanism and the State of Stress in the East African Rift System

Geology of Ethiopia: A Review and Geomorphological Perspectives

The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

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